(4)
(a) The sketch above represents some weld defects in a fabricated
assembly.
- Identify the faults labelled Q, R, S and T.
- State one cause each of any two of the faults.
(b) (i) Sketch a straight soldering iron.
(ii) Label three of its parts.
Most of the candidates avoided this question. The few that attempted it could not provide the required responses to the various parts of the question. The required responses to the various parts of the question are given below:
(ai) Q is undercut
R is lack of fusion/penetration
S is overfilled groove
T is partially filled groove/lack of fusion.
(aii) Causes of Q include:
- excessive weaving;
- incorrect angle of electrode of nozzle;
- current too high.
Causes of R include:
- incorrect joint design;
- too low current;
- melting rod before melting parent metal.
Causes of S include:
- electrode or rod too large;
- low current;
- too slow rate of travel/welding speed.
Causes of T include:
- too rapid rate of travel
- too small an electrode or rod
(bi & ii)
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